The chief of police in a suburb of the wealthy north Mexico city of Monterrey has been gunned down, as authorities struggle to keep a lid on one of the country’s most violent criminal conflicts.

According to reports, German Perez Quiroz, director of public security in Santa Catarina, Nuevo Leon, was working in his office on Monday afternoon when a group of ten ski-masked men carrying assault rifles entered the police station. Upon finding Perez, they shot him several times, killing him instantly. The group then left the facility, abducting three or four employees as they fled.

Nuevo Leon has been the site of an intense fight between the Gulf Cartel and the Zetas over the past year and a half, and the murder rate has spiked as a result. The battle for territory has also placed public servants in the crossfire, as the two gangs seek to intimidate honest officials and to punish those believed to be working for their adversaries.

As InSight Crime has noted, two bodyguards to Nuevo Leon Governor Rodrigo Medina were found dismembered in Monterrey earlier this month. A note left next to the bodies accused them of working for the Zetas.

The mayhem in the Monterrey region is especially worrying for government officials because the city is important to the nation’s economy, and because it had previously been considered exempt from north Mexico’s outbreaks of drug violence.